Most animals had a shot at having a third eye, but blew it in favor of questionably more helpful things, like hair.

Lizards have a little dot at the top of their heads that is called a "parietal eye." This eye is not as complex or as useful as the two in the front of their heads, but it does react to light. Are they eventually going to have a third eye? No. It's just a vestigial trait.

In fact, it looks like most animals — including humans — had a chance at a third eye, and we blew it.